Preparation And Characterization Of 0-3 KNN/PVDF Piezoelectric Composite Films

With the development of science and technology,modern industry began to demand integrated electronic components,and the piezoelectric film with micro-nano scale,especially the composite piezoelectric film combined with ceramic and polymer,has been studied by various industry researchers.Wide attention.However,most of the ceramic phases used in piezoelectric films are lead-based piezoelectric ceramics represented by lead zirconate titanate,which is harmful to the human body and the natural environment.Therefore,it is necessary to study lead-free piezoelectric ceramics as ceramic phases.In this paper,PVDF was used as the matrix,and potassium citrate(KNN)powder prepared by hydrothermal synthesis was added as the ceramic phase.The composite film was prepared by spin coating method.It is then processed by means of corona polarization and the composite film is packaged as a sensor.In this experiment,various characteristics of KNN powder,KNN/PVDF composite film and its sensor were tested in various equipments,and the test results were discussed.The characterization results show that the KNN powder is a spherical aggregate with a size of about 5 ?m,which is a perovskite structure,and the growth of KNN powder belongs to orientation.The KNN powder was controlled by changing the lye,and finally a KNN powder of about 3 ?m was prepared.The PVDF composite film with its ceramic phase has a thickness of about 2 ?m,and the surface of the hemispherical projections is uniformly distributed.The dielectric properties of the composite film gradually increase with the increase of the KNN powder content,which is consistent with the prediction of the theoretical model.Infrared spectroscopy tests show that when the KNN powder content increases,the ? phase content in the composite film decreases.And after the composite film is polarized,the ? phase in the PVDF matrix is converted to the ? phase.Finally,the film is packaged as a sensor,and the tapping force test is performed.The time domain characteristics and frequency domain characteristics of the sensor feedback voltage are obtained.It is confirmed that the principle is the same as that of the capacitor,and it is known that the sensor is sensitive in the range of 10-60 Hz..The sensitivity curve fitted by the least squares method proves that the sensitivity of the KNN/PVDF sensor increases first and then decreases with the KNN powder content.